refactor(页面动画): 优化首页动画元素引用和初始化逻辑

移除未使用的 introCharRefs 引用，改用 gsap.utils.toArray 获取字符元素
将 '.hero-intro-tm' 选择器结果缓存为 tmElement 避免重复查询
为静态元素添加 v-once 指令提升性能
调整部分元素的初始 opacity 和 visibility 状态

app/pages/index.vue

@@ -54,7 +54,6 @@ const loaderRef = ref<HTMLElement | null>(null)
 const loaderBarRef = ref<HTMLElement | null>(null)
 const introRef = ref<HTMLElement | null>(null)
 const introTitleRef = ref<HTMLElement | null>(null)
-const introCharRefs = ref<HTMLElement[]>([])
 const heroStageRef = ref<HTMLElement | null>(null)
 const heroRef = ref<HTMLElement | null>(null)
 const heroPanelRef = ref<HTMLElement | null>(null)
@@ -96,8 +95,9 @@ onMounted(() => {
   }
 
   const introCharElements = gsap.utils.toArray('.hero-intro-char', introElement)
+    const tmElement = introElement.querySelector('.hero-intro-tm')
 
-  if (introCharElements.length === 0) {
+    if (introCharElements.length === 0 || !tmElement) {
       return
     }
 
@@ -210,10 +210,10 @@ onMounted(() => {
           y: 0,
           autoAlpha: 1,
         })
-        .set('.hero-intro-tm', {
+        .set(tmElement, {
           autoAlpha: 0,
         })
-        .fromTo(gsap.utils.toArray('.hero-intro-char', introElement), {
+        .fromTo(introCharElements, {
           yPercent: 110,
           y: 0,
         }, {
@@ -222,7 +222,7 @@ onMounted(() => {
           duration: 0.75,
           stagger: 0.055,
         })
-        .to('.hero-intro-tm', {
+        .to(tmElement, {
           autoAlpha: 1,
           duration: 0.4,
           ease: 'power2.out',
@@ -271,7 +271,7 @@ onMounted(() => {
     gsap.set(introTitleElement, { y: 0, autoAlpha: 1 })
     // 强制清除 CSS 中的 translateY 像素值，避免被 GSAP 解析为固定 y 像素导致一直不可见
     gsap.set(introCharElements, { y: 0, yPercent: 110 })
-    gsap.set('.hero-intro-tm', { autoAlpha: 0 })
+    gsap.set(tmElement, { autoAlpha: 0 })
     gsap.set(heroElement, { yPercent: 100 })
     if (topHeader) {
       gsap.set(topHeader, { yPercent: -140, autoAlpha: 0 })
@@ -336,7 +336,7 @@ onBeforeUnmount(() => {
     :data-demo-user="demoUserName"
     :data-demo-user-role="demoUserRole"
   >
-    <div ref="loaderRef" class="page-loader" aria-hidden="true">
+    <div ref="loaderRef" class="page-loader" aria-hidden="true" v-once>
       <div class="page-loader-content">
         <p>Loading</p>
         <span class="page-loader-line">
@@ -346,14 +346,14 @@ onBeforeUnmount(() => {
     </div>
 
     <div ref="introRef" class="hero-intro" aria-hidden="true">
-      <h1 ref="introTitleRef" class="hero-intro-title" :aria-label="introTitle">
+      <h1 ref="introTitleRef" class="hero-intro-title" :aria-label="introTitle" v-once>
         <span class="hero-intro-word">
           <span
             v-for="(letter, index) in introLetters"
             :key="`${letter}-${index}`"
             class="hero-intro-char-wrap"
           >
-            <span ref="introCharRefs" class="hero-intro-char">{{ letter }}</span>
+            <span class="hero-intro-char">{{ letter }}</span>
           </span>
           <span class="hero-intro-tm">TM</span>
         </span>
@@ -365,7 +365,7 @@ onBeforeUnmount(() => {
       class="hero-stage"
       :style="{ '--hero-pin-distance': `${heroPinDistance}px` }"
     >
-      <section ref="heroRef" class="hero-section">
+      <section ref="heroRef" class="hero-section" v-once>
         <div class="hero-backdrop" aria-hidden="true">
           <div
             v-for="column in heroGalleryColumns"
@@ -455,6 +455,8 @@ onBeforeUnmount(() => {
   overflow: hidden;
   color: #fff;
   background: #000;
+  opacity: 0;
+  visibility: hidden;
   will-change: transform;
 }
 
@@ -495,6 +497,8 @@ onBeforeUnmount(() => {
   font-weight: 700;
   letter-spacing: -0.02em;
   line-height: 1;
+  opacity: 0;
+  visibility: hidden;
 }
 
 .hero-stage {